To identify unknown genetic loci determining alcoholism, we are testing for linkage or association between genetic markers and behavioral phenotypes. The markers are protein polymorphisms, DNA restriction fragment polymorphisms (RFLP's), and classical allozymes and blood antigens. The probability of establishing linkage or association is being maximized by (1) focusing on human alcoholism with impulsivity/aggressivity as a prominent accompanying trait, (2) utilizing mouse genetic models, and (3)\using a large panel of polymorphisms. Markers include RFLP's defined by probes specific for the Y chromosome. These are being tested, using DNA from cell lines established from male alcoholics. In addition, we mapped 40 protein polymorphisms by two-dimensional electrophoresis of the abundant proteins of lymphocytes, fibroblasts, erythrocytes, and serum. We showed two of the unknown loci to be phosphoglucomutase-3 and glyoxalase-1. Our population studies using this technique revealed that the overall level of genetic variability, as indexed by the average heterozygosity of cellular proteins, is betwen 2% and 2.5%, one-third the level previously accepted for the human. In the mouse, we have identified 12 brain polypeptide variants and have successfully correlated 1 of these with resistance to ethanol-withdrawal seizures. We have also shown that the short- and long-sleep mouse strains, widely used to investigate determinants of sensitivity to acute ethanol-induced sedation, are highly inbred, decreasing their usefulness in correlational studies. We are studying the known enzymes of ethanol metabolism, principally the alcohol and aldehyde dehydrogenases, at the protein and DNA levels. In this work, we have recently developed a new technique for the electrophoretic characterization of variants of these proteins: immobiline isolelectric focusing. At the DNA level, we have completed a linkage analysis of an alcohol dehydrogenase RFLP to chromosome 4 markers as well as a preliminary survey of the alcohol dehydrogenase genes present in the hominoid primates.